Although the northern hog suckerHypentelium nigricansis widely distributed throughout the Mississippi and Ohio river basins and is both ecologically and recreationally important, much of its basic ecology is not known. We determined movement and habitat use for 25 fish in the Current River, Missouri, for 1 year using radio telemetry. Seasonal movements were recorded two or three times each week during daylight hours from January to November 1988. Diet movement and habitat use were recorded once each hour for 17 d in winter and 12 d in summer. Mean daily distance traveled was greater in summer (425 m) than in winter (276 m). Home range was greater in winter and spring (812 m) than in summer and fall (426 m). Habitat use changed seasonally from slower, deeper water and smaller substrates during winter to increasing use of taster, shallower water and larger substrates through warmer-water periods. In both seasons, fish had a consistent daily pattern, moving more during the day than at night. Diet patterns of use were distinct. In winter, fish used pool habitat with moderate flow during the day and riffle or edge habitat at night. In summer, fish used run habitat during the day and riffle or edge habitat at night. Patterns of habitat use indicated fish used one area of the river during the day to feed and another at night to rest. Fish remained in their home area during high-flow events but used flooded riparian areas where current velocities were lower. Fish moved up- or downstream short distances (mean = 497 m,N= 7) into spawning areas during late February and early March. This study emphasizes the importance of habitat diversity to accommodate this species' diel and seasonal preferences and the necessity of a connected floodplain for the fish to survive catastrophic events.